Health Level-7 or HL7 refers to international standards for transfer of data between software applications used by various healthcare providers. These different providers, departments, or organizations may operate disparate computer systems to process, share, and organize the different data. It is desirable that these computer systems interface with each other allowing transfer of data between the different computing systems. HL7 is a standard that enables such communication between the computer systems. As technology evolves and more types of information need to be stored or new links need to be made in already stored data, the HL7 standard is updated to reflect the new requirements.
HL7 messages describe healthcare events in a hierarchical manner, with a single message composed of multiple segments. Each segment is composed of multiple fields. Each field may have multiple repetitions. Each repetition may have multiple components, and each component may have multiple subcomponents. Changes to the HL7 standard may disrupt computing systems working with older versions of the standard, rendering those systems incompatible with the new standard.